Your remark is correct, but I don't believe it is helpful for beginner level. First they have to use hips in very exaggerated way simply to learn how to use it.Later on, move of the hips tends to be smaller and smaller while still preserving efficiency of the technique.
From my experience, keeping hips always stable right from the beginning very often leads to stiffness of whole body.
I don't agree with this at all. Moving in the manner Geraldo describes is a teachable skill that anyone can learn, no matter how many years they've been doing aikido, and it doesn't involve moving from the hips at all. In fact probably much easier to teach beginners than someone who had spent years of their budo career (such as me) generating power from the hips. I just don't see the point of teaching something that's just....wrong, only to have them spend even more time unlearning it later.